1. Field of the Invention
The present invention relates to an actinic-ray- or radiation-sensitive resin composition, an actinic-ray- or radiation-sensitive film therefrom and a method of forming a pattern. More particularly, the present invention relates to an actinic-ray- or radiation-sensitive resin composition that is suitable for use in, for example, an ultramicrolithography process applicable to a process for manufacturing a super-LSI or a high-capacity microchip, a process for fabricating a nanoimprint mold, a process for producing a high-density information recording medium, etc., and other photofabrication processes, and relates to an actinic-ray- or radiation-sensitive film therefrom and a method of forming a pattern.
2. Description of the Related Art
Heretofore, the microfabrication by lithography using a photoresist composition is performed in the process for manufacturing semiconductor devices, such as an IC and an LSI. In recent years, the formation of an ultrafine pattern in the submicron region or quarter-micron region is increasingly required in accordance with the realization of high integration for integrated circuits. Accordingly, the trend of exposure wavelength toward a short wavelength, for example, from g-rays to i-rays and further to a KrF excimer laser light is seen. Further, the development of lithography using electron beams, X-rays, EUV light or the like, other than the excimer laser light, is now being promoted.
Isolated patterns are often used in contemporary logic devices and the like. Isolated patterns include an isolated line pattern (isolated left pattern) and an isolated space pattern (isolated void pattern). In both thereof, fining is being promoted. In particular, when it is intended to form a fine isolated space pattern, it is preferred to raise the dissolution contrast in an alkali developer from the viewpoint of resolution. However, from the viewpoint of comprehensive performance as a resist, it is also needed to satisfy the roughness characteristic, exposure latitude, pattern shape, process-acceptable focus fluctuation range (depth of focus), etc. It has been extremely difficult to simultaneously satisfy the resolution and these.
Further, especially the electron beam lithography is positioned as the next-generation or next-next-generation pattern forming technology. Positive resists of high sensitivity and high resolution are required for the lithography. Specifically, increasing the sensitivity is a very important task to be attained for the shortening of wafer processing time. However, the pursuit of increasing the sensitivity with respect to the positive resists for electron beams is likely to invite not only the lowering of resolving power but also the deterioration of line edge roughness. Thus, there is a strong demand for the development of resists that simultaneously satisfy these properties. Herein, the line edge roughness refers to the phenomenon that the edge at an interface of resist pattern and substrate is irregularly varied in the direction perpendicular to the line direction due to the characteristics of the resist, so that when the pattern is viewed from above, the pattern edge is observed uneven. This unevenness is transferred in the etching operation using the resist as a mask to thereby cause poor electrical properties resulting in poor yield. Especially in the nanoregion of 0.25 μm or less, the line edge roughness is now an extremely important theme in which improvement is to be attained. High sensitivity is in a relationship of trade-off with good pattern shape and good line edge roughness. How to simultaneously satisfy all of them is a critical issue.
In the lithography using X-rays, EUV light or the like as well, it is an important task to simultaneously satisfy the high sensitivity, good pattern shape, good line edge roughness and resolution of an isolated space pattern. Solving this problem is required.
The use of resins in which a moiety that upon exposure to light generates an acid (also referred to as a photoacid generating group) is introduced in the principal chain or a side chain thereof is being studied (for example, patent references 1 to 6). However, the current situation is that simultaneously satisfying the high sensitivity, good pattern shape and good line edge roughness is not ample.
Among the literature, patent references 2 to 6 disclose resins containing in the same molecule a photoacid generating group and a group capable of increasing its solubility in an alkali developer by acid decomposition. However, the sensitivity to electron beams, X-rays or EUV light has been hardly adequate.
In summing up, the current situation is that simultaneously fully satisfying the high sensitivity, high resolution, good pattern shape, good line edge roughness, etc. in the lithography using electron beams, X-rays or EUV light cannot be attained by any combination of now generally known technologies.